#include <stdio.h>

#define in "operatii.in"
#define out "operatii.out"

typedef long long int INT;
INT X, Y, NRSOL;
INT n;

int main()
{
    freopen( in, "r", stdin );
    freopen( out, "w", stdout );
    
    NRSOL = 0;
    scanf( "%lld", &n );
    
    X = 0;
    int i;
    for ( i = 1; i <= n; ++i )
    {
        scanf( "%ld", &Y );
        if ( Y > X ) NRSOL += (Y - X);
        X = Y;
    }
    
    printf( "%lld\n", NRSOL );
    return 0;
}