By Jill Lawliss

CANNES, France (AP) --

 From "M.A.S.H." to "Three Kings," the humor that erupts amid the horrors of war has been a tough but tempting subject for filmmakers.

Spanish director Fernando Leon de Aranoa tackles the dark comedy of conflict in "A Perfect Day," which stars Benicio Del Toro and Tim Robbins as aid workers trying — and often failing — to do some good during the 1990s Balkan wars.

The director, who has shot documentaries for humanitarian groups, drew on that experience for the film, which aims to capture the adrenaline — and the absurdity — of life in conflict.

"The first casualty in war is common sense," said Leon de Aranoa, whose gritty films include the unemployment drama "Mondays in the Sun" with Javier Bardem.

"If these guys mean something to me in the movie, it is just common sense," he said. "They are trying to put some kind of order in chaos."

The plot of Leon de Aranoa's English-language debut involves an attempt to remove a corpse from a village well. It seems a simple task, but everything from a shortage of rope to local enmities to U.N. bureaucracy frustrates the aid team's efforts.

The filmmaker said he chose not to put the characters into "epic or heroic situations."

"Even if they fail — they fail a lot in the movie — the heroism is just to try," he said on a hotel terrace in Cannes, where the film is playing in Directors' Fortnight, a lineup separate from the main competition that seeks distinctive voices from around the world.

"A Perfect Day" veers from pathos to broad comedy to near-satire, played out to a hard-rock soundtrack.

"That balance between humor and tenderness and darkness is my cup of tea in movies," said Leon de Aranoa, who is slated to direct a biopic of drug kingpin Pablo Escobar with Bardem and Penelope Cruz. "This was the big challenge for the movie. … It has to work, the change from drama to humor."

The film's tonal shifts can feel abrupt, but it has been applauded for taking risks — and for being one of the few movies to feature aid workers as heroes.

Its originality appealed to Del Toro, the film's linchpin as the humane but weary Mambru. Melanie Thierry and Olga Kurylenko play the — somewhat underwritten — female members of the group.

"You've got a lot of movies about cops and robbers and all that stuff," Del Toro said. "Here's a movie that the main focus is aid workers."

The Puerto Rican actor is also in Cannes with Denis Villeneuve's Mexican drug cartel thriller "Sicario," in which he plays a mysterious Colombian involved in the war on drugs. And he provides the voice of The Snake in animated Cannes entry "The Little Prince."

Del Toro said he tries to balance big projects with smaller ones.

"When you do a smaller film there's less people making decisions," said the actor, who had a rocky big-budget movie experience with the horror clunker "The Wolfman."

"I tried to include myself in the people making decisions while I was doing 'The Wolfman,' and I didn't get in the room that much," he said. "In an independent movie, I can have a little bit more say. And you know what? I should."

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